1. Field of the Invention
The present invention relates to a hybrid disc of a dye membrane recording type having a read-only area and a recordable area.
2. Description of the Related Art
A read-only optical disc, such as a CD (Compact Disc) of a read only type has become widespread. Such a read-only optical disc has phase pits to record information. Each phase pit is formed such that its depth is equal to one-four wavelength xcex of a light beam used for reproduction, i.e., xcex/4.
On the other hand, a recordable optical disc is developed. Especially, as one type of the recordable optical disc, a write once type optical disc, such as a CD-R (CD-Recordable) and the like is frequently developed. Such a write once type optical disc has a recording layer composed of a dye membrane. When information is recorded on the write once type optical disc, a light beam modulated such that its intensity is changed depending on the information is emitted onto the recording layer. Thereby, reflectance of the dye membrane at the irradiated part is changed. Thus, the information is recorded on the disc. When reproducing, the recorded information is reproduced on the basis of a change of reflectance.
Here, in the above mentioned write once type optical disc, the intensity of the light beam used for recording is alternatively changed between a first intensity and a second intensity. Namely, when the information to be recorded onto the disc is a high level, the intensity of the light beam is the first intensity. When the information is a low level, the intensity of the light beam is the second intensity. The second intensity is weaker than the first intensity, and the second intensity is roughly or accurately equal to the intensity of a light beam used for reproduction. When the information is recorded on the disc, reflectance of the dye membrane is changed by switching over the intensity of the light beam between the first intensity and the second intensity. In order to increase the intensity of the light beam, it is preferable that the light beam is efficiently used.
Furthermore, when the information is recorded on the write one type optical disc, it is necessary that the light beam is accurately emitted on the target track in order to record the information on it accurately. Therefore, a tracking control is performed. Various kinds of methods to perform the tracking control have been developed. In view of the efficiency of the light beam, a push-pull method is preferably used as the tracking control for recording information on the write once type optical disc. In the push-pull method, a single light beam is used for both recording and the tracking control. In case that the tracking control is performed by using the push-pull method, in order to increase a level of a tracking error signal to the maximum, it is necessary that height (depth) of the information track of the write once type optical disc is one-eight waveform xcex of the light beam, i.e., xcex/8.
Therefore, in the write once type optical disc, in view of both recording and reproduction, a predetermined value between xcex/8 to xcex/4 is set as the depth of the information track.
Here, in view of the recent development of multimedia, an optical disc having the function of the read-only optical disc and the function of the write once type optical disc is desired.
However, it is difficult to realize such an optical disc (Hereinafter, it is referred to as a xe2x80x9chybrid discxe2x80x9d.). The reason is that the depth of the phase pit of the read-only optical disc is different from that of the information track of the write once type optical disc. Namely, the depth of the phase pit of the read-only optical disc is xcex/4, but the depth of the information track of the write once type optical disc is the predetermined value between xcex/8 to xcex/4 (not xcex/4). It is very difficult in view of a yield to form the phase pit and the information track each having different depth on a single disc.
It is therefore a first object of the present invention to provide a hybrid type dye record medium which can be easily produced.
Furthermore, it is a second object of the present invention to provide a record disc producing apparatus which can easily produce a record disc, such as a hybrid type dye record medium.
Moreover, it is a third object of the present invention to provide an information reproducing apparatus which can surely reproduce information recorded on a hybrid type dye record medium.
According to the present invention, the above mentioned first object can be achieved by a dye record medium provide with: a substrate having a track-forming-surface divided into a read-only area and a recordable area; a reproducing track formed on the track-forming-surface in the read-only area, and constructed by an arrangement of a plurality of pits, each of the pits comprising a dye material, having a shape corresponding to reproducing information, and having a constant predetermined height; and a recording/reproducing track formed on the track-forming-surface in the recordable area, and extending continuously, the recording/reproducing track comprising the same dye material as each of the pits, and having the same predetermined height as each of the pits.
Namely, the dye record medium has a two areas, i.e., the read-only area and the recordable area. In the read-only area, reproduction information is recorded on the track-forming-surface in advance as the reproducing track constructed by the arrangement of the plurality of pits. In the read-only area, reproducing the reproducing information is possible, but recording a new information is impossible. On the other hand, in the recordable area, both recording new information and reproducing the recorded information are possible.
In the read-only area, the reproducing track is formed. The reproducing track is constructed by the arrangement of the plurality of the pits. Each pit has a shape corresponding to the reproducing information. Namely, the shape of each pit is changed depending on conditions of the reproducing information. Thereby, when the reproducing track is irradiated with the light beam, reflectance of the light beam is changed on the basis of the shape of each pit. Furthermore, each pit is composed of at least dye material. Moreover, each pit having a constant predetermined height. The height means a length between the track-forming-surface and the top of the pit.
In the recordable area, the recording/reproducing track is formed. Unlike the reproducing track, the recording/reproducing track continuously extends. Namely, as the recording/reproducing track does not have pits, there is no break or gap in the recording/reproducing track.
Furthermore, the recording/reproducing track is compose of at least the same dye material as each of the pits of the reproducing track. Moreover, the recording/reproducing track has the same predetermined height as each of the pits of the reproducing track.
Accordingly, when the dye record medium is produced, the reproducing track and the recording/reproducing track can be simultaneously produced in the same process. As a result, it is possible to simplify the production process of the dye record medium and to produce the dye record medium easy.
Moreover, since the reproducing track is constructed by the arrangement of the plurality of pits each having the shape corresponding to the reproducing information, it is possible to reproduce the reproducing information surely.
Furthermore, the top surface of each of the pits and the top surface of the recording/reproducing track may be in the same plane. Accordingly, when the dye record medium is produced, the reproducing track and the recording/reproducing track can be simultaneously produced in the same process. As a result, it is possible to produce the hybrid type dye record medium easy.
Moreover, the substrate of the dye record medium has: a base; a reflective layer formed on the base, for reflecting the light beam; and a dye membrane formed on the reflective layer, a surface of the dye membrane is the track-forming-surface, each of the pits is integrated with the dye membrane, and the recording/reproducing track is integrated with the dye membrane.
Thus, when the dye record medium is produced, each of the pits and the recording/reproducing track can be simultaneously produced in the same process. Accordingly, it is possible to produce the hybrid type dye record medium easy.
According to the present invention, the above mentioned second object can be achieved by a record disc producing apparatus for producing a record disc, the record disc having: a disc shape substrate having a track-forming-surface divided into a read-only area and a recordable area; a reproducing track formed on the track-forming-surface in the read-only area, and constructed by an arrangement of a plurality of pits, each of the pits having a shape corresponding to reproducing information; and a recording/reproducing track formed on the track-forming-surface in the recordable area, and extending continuously, the record disc producing apparatus having: a rotation device for rotating the record disc; a sending device for sending the record disc in a radial direction of the recording disc; and an emitting device for emitting a first light beam having an intensity modulated on the basis of reproducing information when the reproducing track is formed in the read-only area, emitting a second light beam having a constant intensity when the recording/reproducing track is formed in the recordable area, and controlling the intensity of the first light beam and the intensity of the second intensity such that both the reproducing track and the recording/reproducing track have the same height.
Namely, the rotation device rotates the record disc, while the sending device sends the record disc in the radial direction of the record disc. The emitting device emits the light beam to the record disc, while these operation is performed. The emitting device emits the first light beam having an intensity modulated on the basis of reproducing information, when the reproducing track is formed in the read-only area. On the other hand, the emitting device emits the second light beam having a constant intensity when the recording/reproducing track is formed in the recordable area. Furthermore, the emitting device controls the intensity of the first light beam and the intensity of the second intensity such that both the reproducing track and the recording/reproducing track have the same height. Thus, the reproducing track and the recording/reproducing track can be easily formed, and the height of the reproduce track and the height of the recording/reproducing track can be easily equalized with each other.
According to the present invention, the above mentioned third object can be achieved by an information reproducing apparatus for reproducing reproducing information recorded on a dye record disc, the dye record disc comprising: a disc shape substrate having a track-forming-surface divided into a read-only area and a recordable area; a reproducing track formed on the track-forming-surface in the read-only area, and constructed by an arrangement of a plurality of pits, each of the pits comprising a dye material, and having a shape corresponding to the reproducing information; and a recording/reproducing track formed on the track-forming-surface in the recordable area, and extending continuously, the recording/reproducing track comprising the same dye material as each of the pits, the information reproducing apparatus having: an initial light emitting device for emitting an initial light beam to all of the pits before reproduction, in order to change reflectance of all of the pits; a reproducing light emitting device for emitting a reproducing light to each of the pits; a receiving device for receiving a reflective light of the reproducing light reflected by the reproducing track, and generating a receiving signal corresponding to the received reflective light; and a reproducing device for reproducing the reproducing information on the basis of the receiving signal.
Namely, before the information reproducing apparatus actually reproduces the reproducing information recorded in the read-only area, the initial light emitting device emits the initial light beam to all of the pits. Thereby, reflectance of all of the pits are changed. This enables to reproduce the reproducing information.
Thereafter, the reproducing light emitting device emits the reproducing light to each of the pits, and the receiving device receives the reflective light of the reproducing light reflected by the reproducing track. Furthermore, the receiving device generates a receiving signal corresponding to the received reflective light. Next, the reproducing device reproduces the reproducing information on the basis of the receiving signal.
Accordingly, it is possible to detect the reproducing information from the dye pits accurately, and to reproduce the reproducing information surely.
According to the present invention, the above mentioned third object can be also achieved by an information recording/reproducing apparatus for recording recording information onto a dye record disc and reproducing reproducing information recorded on the dye record disc, the dye record disc having: a disc shape substrate having a track-forming-surface divided into a read-only area and a recordable area; a reproducing track formed on the track-forming-surface in the read-only area, and constructed by an arrangement of a plurality of pits, each of the pits including a dye material, and having a shape corresponding to the reproducing information; and a recording/reproducing track formed on the track-forming-surface in the recordable area, and extending continuously, the recording/reproducing track including the same dye material as each of the pits, the information recording/reproducing apparatus having: an initial light emitting device for emitting an initial light beam to all of the pits before reproduction, in order to change reflectance of all of the pits; a reproducing light emitting device for emitting a reproducing light to each of the pits; a receiving device for receiving a reflective light of the reproducing light reflected by the reproducing track, and generating a receiving signal corresponding to the received reflective light; a reproducing device for reproducing the reproducing information on the basis of the receiving signal; and a recording light emitting device for emitting a recording light modulated on the basis of the recording information onto the recording/reproducing track, in order to record the record information onto the recording/reproducing track by changing reflectance of the recording/reproducing track.
Thus, the recording information is recorded by changing reflectance of the recording/reproducing track. Accordingly, the reproducing information recorded in the read-only area and information recorded on the recording/reproducing track in the recordable area can be reproduced respectively, by using the same reproducing light beam.
Furthermore, the initial light emitting device emits the initial light beam having an intensity not more than an intensity of the recording light and more than an intensity of the reproducing light. Thereby, the recording light emitting device, the reproducing light emitting device, and the initial light emitting device can be united, and it is possible to simplify the configuration of the apparatus.
According to the present invention, the above mentioned third object can be also achieved by an information reproducing method of reproducing reproducing information recorded on a dye record disc, the dye record disc having: a disc shape substrate having a track-forming-surface divided into a read-only area and a recordable area; a reproducing track formed on the track-forming-surface in the read-only area, and constructed by an arrangement of a plurality of pits, each of the pits including a dye material, and having a shape corresponding to the reproducing information; and a recording/reproducing track formed on the track-forming-surface in the recordable area, and extending continuously, the recording/reproducing track including the same dye material as each of the pits, the information reproducing method having the processes of: emitting an initial light beam to all of the pits before reproduction, in order to change reflectance of all of the pits; emitting a reproducing light to each of the pits; receiving a reflective light of the reproducing light reflected by the reproducing track, and generating a receiving signal corresponding to the received reflective light; and reproducing the reproducing information on the basis of the receiving signal.
Namely, before the information reproducing apparatus actually reproduces the reproducing information recorded in the read-only area, all of the pits are irradiated with the initial light. Thereby, reflectance of all of the pits are changed. This enables to reproduce the reproducing information.
Thereafter, each of the pits are irradiated with the reproducing light, and the reflective light of the reproducing light reflected by the reproducing track is received. Furthermore, the receiving signal corresponding to the received reflective light is generated. Next, the reproducing information on the basis of the receiving signal is reproduced.
Accordingly, it is possible to detect the reproducing information from the dye pits accurately, and to reproduce the reproducing information surely.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when lead-in conjunction with the accompanying drawings briefly described below.